1. Field of the Invention
In general, the present invention relates to breaker circuits and other circuit configurations that are used to prevent an over-voltage condition between a power supply and circuits that are powered by that power supply. More particularly, the present invention relates to circuit breaker circuits and other such circuit configurations that can be used in direct current applications.
2. Prior Art Description
In the recent past, the strongest direct circuit source a person would typically encounter would be the twelve-volt electrical systems of an automobile. However, with the advent of hybrid automobiles, electric automobiles, solar panels and the like, there now exist many common direct current applications that can carry over one-hundred volts.
Along with the increase of direct current applications has come the need for direct current circuits to safely control the flow of electricity. One of the most basic control circuits is a circuit breaker that prevents power surges from damaging downstream components. The prior art is replete with various circuit breaker circuits that are designed for alternating current applications. However, few are capable of operating with direct current. Circuits that are designed for direct current tend to be current shunt monitor circuits, such as crowbar circuits. Such circuits operate by putting a short circuit or low resistance path across a voltage source. This is typically achieved using a thyristor, silicon controlled rectifier or thyratron. Once the short is achieved, the flow of current is stopped by the blowing of a line fuse. As a consequence, the line fuse must be replaced before the downstream circuits can again operate.
Due to the components used in prior art current shunt monitor circuits, such circuits cannot operate in applications where the direct current is in excess of sixty volts. Consequently, such circuits are not practical in the most common applications of electric automobiles and solar power generators.
In direct voltage applications, over sixty-volts, electro-mechanical breakers are commonly used. However, such devices are prone to contact welding, arcing and sparking. As such, there are safety concerns in many applications where such failures can start fires.
A need therefore exists for a solid state circuit breaker that does not use electro-mechanical parts, yet can operate in applications in excess of one-hundred volts DC. This need met by the present invention as described and claimed below.